Optical metering means for gas using a sliding tube



Feb. 21, 1950 J. H. RAMSER 2,498,506

OPTICAL METERING MEANS FOR GAS USING A SLIDING TUBE Filed June 11, 19473 Sheets-Sheet 1 Figure 1 INVENTOR.

John H. Ramser J. H. RAMSER 3 Sheets-Sheet 2 INVENTOR.

BKYIOILII H. Ru IILSOI fli'i'otnegf 5 5V -w I,

Feb. 21, 1950 OPTICAL METERING MEANS FOR GAS USING A SLIDING TUBE FiledJune 1].. 1947 IJTTEST 1M3 Feb. 21, 1950 J. H; RAMSER 2,

OPTICAL METERING MEANS FOR GAS USING A SLIDING TUBE Filed June 11. 19473 Sheets-Sheet 3 w'unnlunnnh HTTEST INVENTOR.

John If. Rams er A l' I'm-neg Patented Feb. 21, 1950 OPTICAL METERINGMEANS FOR GAS USIN A SLIDING TUBE v John H. Ramser, Chester, Pa.,assignor to The Atlantic Refining Company, Philadelphia, Pa., acorporation of Pennsylvania Application J une 11, 1947, Serial No.753,983

Claims.

The present invention relates to -improvements in apparatus adapted todetermine the amount of entrained material in a fluid, particularly todetermine the amount of entrained solids in a gas, and-more particularlyto determine the amount of catalyst fines present in the flue gas from aregenerator of a'fluid catalytic cracking unit.

In the operation of a fluid catalytic cracking unit, finely dividedcatalyst particles are injected into thefluid charge stream and,suspended therein, are carriedt'o the reactor where, after theiractivity has been spent, such particles are caused to settle out and toreturn to the regenerator. Hot air and steam blown through theregenerator remove coke or like matter deposited on the catalyst. As thehotair and steam are removed from the regenerator, such gases are passedthrough a cyclone separator and a precipitator to remove the catalystparticles remaining entrained therein. Although the greater part of thecatalyst present in the gas is removed by such means there still remainsa portion thereof suspended in said gas when it enters the flue leadingfrom the precipitator. As the catalyst can be regenerated and usedrepeatedly, any loss thereof before it has become completely spent willincrease the cost of the process being carried out. It is, therefore, ofeconomic importance to keep the loss of catalyst at a minimum. Since theconcentration of catalyst in the flue gas varies with operatingconditions such as regenerator gas rate, water and ammonia content ofthe gas, and other factors, it is desirable to know the exactconcentration of catalyst in the flue gas in order that suchconcentration can be held to a minimum by the control of such factors.

Heretofore, the concentration of catalyst fines in the flue gas of afluid catalytic cracking unit has been determined by spot testsutilizing porous filters. This method is, however, subject'to certaininherent defects, chief among them being the necessity for laboriouscalculations each time the test is run, possibility of error, andinability to determine the time variation of catalyst concentration inthe gas unless frequent tests are run with a resulting increase inlabor. Furthermore,

it has, in the past, been impossible to determine the total amount ofcatalyst lost over any given period of time without resort to frequenttests stantaneous determination of the concentration of catalyst finesin the flue gas from a precipitator of a fluid catalytic cracking unit.

Another object of the invention is to provide means adapted for thecontinuous determination of the concentration of catalyst fines in theflue gas from a fluid catalytic cracking unit precipitator at a givenpoint within the stack of such unit.

A further object of the invention is to provide means whereby a readingfor a zero concentration of catalyst can be obtained without interferingwith the normal operation of the catalytic cracking unit.

Other objects of the invention will be apparent from the description andclaims which follow.

The theory underlying the development of the present invention is thatthe actual concentration of catalyst fines at all points of a crosssection of the flue gas stream in the stack is practically constant atany given instant of time even though the velocity of such gas streammay vary widely from point to point. If a beam of light of intensity Iois sent through the flue gas stream, the intensity of the transmittedlight I is lower than 10 as a consequence of partial absorption andscattering of light by the catalyst particles in the flue gas. Sinceabsorption and scattering of light by solid particles is independent ofthe state of motion of such particles, the intensity of the transmittedlight is a function only of the concentration of the particles and thesize thereof. Since the particle size varies only within narrow limitsthe relationship between transmitted light intensity and concentrationcan be determined for a given length of absorption path and giveninitial intensity of light; thus unknown concentrations may be instantlyread or recorded by means of the intensity of the transmitted light.

In the drawing like numerals are used to designate like parts.

Figure 1 is a front elevational view exemplifying the apparatuspartially in cross section.

Figure 2 is an enlarged top view partially in cross section taken alongthe line 2-2 in Figure 1.

Figure 3 is an enlarged cross sectional view of air injector I"! shownin Figure 1.

Figure 4 is a top view, partially in cross section, of a modification ofthe apparatus illustrating a single tube for checking the zero readingof the optical system.

In the drawing, 4 represents a duct or stack carrying the flue gas inwhich the finely divided catalyst is suspended. Pipe flange 5 is affixedat an aperture 6 in the wall of duct 4 by welding or by other suitablemeans and has fastened thereto, as by bolts 1, or by other suitablemeans, apertured plate 8. Casing 9 extends through apertured plate 8 andis fastened thereto by welding or by other suitable means. Tube I6 isslidably' disposed within casing 9 and projects beyond the around pipel6. Passage of air from air injector |'1 into pipe i6 is permitted byholes 20 in said injector, tubes 2|, and openings 22 circumferen-.

.tially spaced in the wall of pipe I6. Formed as an integral part ofpipe I6 is flexible metalbellows 23, the. purpose of which will bediscussed hereinafter. i

Flange 24 on the outer end of pipe I6 is affixed, as by bolts 25, toflange 26 on light source pipe 21. Positioned between flange 24 andflange 26 and adapted to blank oif light source pipe 21 from pipe |6when so desired is flgure 8 flange 28.

Detachably aiflxed to the outer end of light source pipe 21 is lightsource housing 29 having positioned internally thereof window 39 capableof transmitting light but preventing admission of air from light sourcepipe 21. Also provided within light source housing 29 are'light source 3I such as, for example, a tungsten filament lamp or the like, andparabolic mirror 32 aflixed to housing 29 as at 33.

For purposes of support, column 34 is provided.

Plate 35 on top-of such column and affixed thereto by angle irons suchas36 bears slidable bracket 31 which, by means of bolt 38, is removablyattached to fin 39 welded, orfastened by other suitable means, to lightsource pipe 21. Further support for light source housing 29 is providedby L-shaped support 40 detachably aflixed to the underside of suchhousing by bolt 4|, such .support extending downward through plate 35and being affixed to angle iron 42, by any suitable means which willpermit either vertical or horizontal movement of housing 29, if desired.

Pipe flange 43 is affixed at aperture 44 in the wall of duct 4 bywelding or by other suitable means, and has fastened thereto, as bybolts 45, or other suitable means, apertured plate 46. It will beapparent by reference to-the drawing. particularly Figures 1 and 2 thataperture 44 is formed in the wall of duct 4 at a diametrically,

opposed point to aperture 6 so that pipes 9 and 41 are coaxiallyarranged. Casing 41 extends through apertured plate 46 and is fastenedthereto by welding or other suitable means. Tube 48 is slidably disposedwithin casing 41 and projects beyond the inner end thereof adjacentaperture 44 in duct 4. Handles 49 and 56 slidably extend throughapertured plate 46 andare affixed to tube 48, the purpose of tube 48 andhandles 49 and 56 being more fully discussed hereinafter.

The outer end of casing 41 is externally flanged as at and detachablyafiixed, as by bolts 52, to flange 53 on pipe 54. Air injector 55,provided with inlet 55 controlled by valve 51 is disposed around pipe54. Air injector 55 is, in all respects, identical with air injector l1shown in detail in Figure 3. Formed as an integral part of pipe 54 isflexible metal bellows 68, the purpose of which will be discussedhereinafter.

External flange 59 on the outer end of pipe 54 is affixed, as by bolts66, to flange 6| on light receivin plpe 62. Positioned between flange 59and flange 6| and adapted to blank off lightreceiving pipe 62 when sodesired is flgure 8 flange 63.

Detachably afllxed to the outer end of light receiving pipe 62 is lightsensitive element housing 64 having positionedinternally thereofplanoconvex lens 65 effectually preventing the admission of air fromlight receiving pipe 62-but permitting the passage of light. Lightsensitive element 66, such as a thermopile, or the like, is positionedwithin light sensitive element housing 64 and is connected by wires 61and 68 to'output meter 69, such as, for example, a millivoltpotentiometer or the like.

For purposes of support, column 16 is provided.

Plate 1| on top of such column and affixed thereto by angle irons 12bears slidable bracket 13 which, by means of bolt 14, is removablyattached to fin 15 welded, or fastened by other suitable means, to lightreceiving pipe 62. Further support for light sensitive element housing64 is provided by L-shaped support 16 detachably aflixed to theunderside of such housing by bolt 11, the support extending downwardthrough plate 1| and being aflixed to angle iron 18 by-any suitablemeans which will permit either horizontal or vertical movement ofhousing 64, if desired.

It will readily be understood that, while the device described abovepresents a preferred embodiment of the invention, certain variations canbe made without departing from the scope 'of the appended claims. Forexample, although a tungsten filament lamp, a thermopile, and amillivolt potentiometer have been specified as light source 3|, lightsensitive element 66, and output meter 69, respectively, any combinationreaching a similar result can be used. Among such other combinationsthat might suggest themselves to those conversant with the art are amercury arc lamp, a photocell of the barrier layer type, and amicroammeter; or a sodium vapor lamp, a photoelectric tube, and anamplifier connected to a suitable current or voltage measuring device.

The operation of the device is as follows:

As the flue gas-carrying an unknown concentration of catalyst passesthrough duct 4, a light beam of constant intensity emitted by lightsource 3| and reflected in parallel rays by parabolic mirror 32 emergesfrom light source housing 29 throughwindow 36 into light source pipe 21,passes through pipe I 6 and tube Ill and thence enters duct 4. I Thelight beam traverses the known diameter of duct 4, enters slidable tube48 positioned within casing 41 and passes through pipe 54 into lightreceiving pipe 62. The total transmitted light is focusedby-plano-convex lens 65 upon light sensitive element 66 in lightsensitive element housing 64. The electromotive force genstantaneousconcentration of catalyst in the flue gas may be determined byconverting the reading of output meter 69 into concentration by use of acalibration curve or other suitable means. If so desired, output meter69 can be calibrated directly in terms of catalyst concentration.

In order to record accurately the concentration of catalyst in the fluegas, the intensity of the light beam must be kept constant at all times.Air injectors I1 and 55 are adapted to achieve this end. The injectionof air into pipe I6 and pipe 54 through the respective injectors givesrise to a pressure in such pipes which is positive in relation to thepressure in duct 4 and results in a smooth, uniform flow of air fromsaid pipes into said duct. Such being the case, the accumulation ofcatalyst particles or moisture in the light path or on window 30 andplano-convex lens 85 will be inhibited.

The intensity of the light beam for a zero concentration of catalyst(upon which intensity all other calculations are based) can bedetermined without interfering with the flow of flue gas through duct 4.By means of handles II and [2, tube In slidably positioned within casing9, is advanced into duct 4. Similarly tube 48 slidably positioned withincasing 41 is advanced by handles 49 and 50 until a junction is made withtube In, thereby providing a passage, substantially free of catalystparticles through which the light beam can pass. A reading can then beobtained on output meter 69 and compared with the original reading for azero concentration of catalyst. Ifthe readings do not coincide theintensity of the light beam'isreadjusted to its original value byvarying the intensity of light source 3|. Once said original reading hasbeen obtained, the slidable tubes are retracted to their inoperativepositions within casings 9 and 41 respectively. It is apparent that,instead of two slidable tubes such as 10 and 48, one tube can be used ifof sufficient length to span the entire diameter of duct 4. This isillustrated in Figure 4, where casing 41 is shortened since noextendable tube is disposed therein, and the opposite casing 9 islengthened to accommodate the lengthened tube l0 which may be extendedacross duct 4 by handles l l and I2, thus making contact with the innerend of casing 41, and providing a light path free of solids. Regardlessof whether the double-tube or single tube zeroing arrangement is used,airis continuously injected during the extension of the tube or tubesacross the conduit 4 in order to clear the tube or tubes of suspendedsolids which might otherwise accumulate therein.

It has been found that, after an extended period of operation, thereading for zero concentration of catalyst is less than the originalreading, due to the slow accumulation of catalyst on windoiw 30 andplano-convex lens 65. As a result, it is necessary to clean window 30and planoconvex lens 65. In such case figure 8 flanges 28 and 63 areturned until the blank portions, thereof are seated between light sourcepipe 21 and pipe I6, and light receiving pipe 62 and pipe 54respectively, thus blanking oif light source pipe 21 and light receivingpipe 65 from duct 4. Thus, window 30 and piano-convex lens 85 can beremoved from light source housing 29 and light sensitive element housing64, respectively, without halting normal operation of duct 4 orpermitting flue gas or catalyst particles to enter the respectivehousings.

The accurate adjustment of the apparatus to provide a continuous pathfrom light source 3| to light sensitive element 66 can be readilyaccomplished by virtue of slidable brackets 37 and I3 afiixed to lightsource pipe 21 and light receiving pipe 62, respectively. By raising orlowering light source housing 29 and light sensitive element housing 64with respect to brackets 31 and 13 respectively, and adjusting bolt 38with respect to bracket 3'! and bolt I4 with respect to bracket 13, apath through which the light beam can pass with no obstruction otherthan the entrained catalyst is obtained. Furthermore, such adjustmentcan also be obtained by moving housing 29 and support 40 relative toangle iron 42, and housing 64 and support 16 relative to angle iron 18.

Bellows 23 and 58 on pipes I6 and 54, respectively, are adapted tominimize the transfer of vibration and heat from duct 4 to the more.sensi-' tive parts of the device, namely, light source 3| and lightsensitive element 66 by reason of their flexibility, thinness of wall,and large surface area.

The examples here given and the particular description set forth arepresented in order to illustrate how the invention may be applied. Otherforms and variations coming within the scope of the appended claims willreadily suggest themselves to those skilled in the art.

Iclaim: I

1. An optical system for determining the concentration of entrainedsolids in a gas which comprises a duct having opposed openings in thewalls thereof, pipes associated with said openings, a light sourcepositioned within one of said pipes, and a light sensitive elementpositioned within the other of said pipes, a tube slidably mountedwithin at least one of. said pipes and extendable therefrom at rightangles into said duct for selectively excluding entrained solids fromthe portion of the path within said duct traversed by light passing fromsaid light source to said light sensitive element withoutsubstantial'interference with the normal passage of said entrainedsolids through said duct, and means for creating a positive gas flowfrom said pipes and said tube into said duct to remove entrained solidswhen said tube is extended into said duct.

2. An optical system for determining the concentration of entrainedsolids in a gas which comprises a duct having opposed openings in thewalls thereof, pipes associated with said openings,

a light source positioned within one of said pipes, and a lightsensitive element Positioned within the other of said pipes, a tubeslidably mounted within one of said pipes and extendable therefrom atright angles into said duct to contact the other of said pipes forselectively excluding entrained solids from the portion of the pathwithin said duct traversed by light passing from said light source tosaid light sensitive element without substantial interference with thenormal passage of said entrained solids through said duct, and means forcreating a positive gas flow from said pipes and said tube into saidduct to remove entrained solids when said tube is extended into saidduct.

3. An optical system for determining the concentration of entrainedsolids in a gas which comprises a duct having opposed openings in thewalls thereof, pipes associatedwith said openings, a light sourcepositioned within one of said pipes, and a light sensitive elementpositioned within the other of said pipes, a tube slidably mountedwithin each of said pipes and extendable therefrom at right angles intosaid duct to contact the other tube for selectively excluding entrainedsolids from the portion of the path within said duct'traversed by lightpassing from said light source to said light sensitive element withoutsubstantial interference with the normal passage of said entrainedsolids through said duct, and means for creating a positive gas flowfrom said pipes and tubes into said duct to remove entrained solids whensaid tubes are extended into said duct.

4. An optical systemfor determining the concentration of entrainedsolids in a gas which comprises a duct having opposed openings in thewalls thereof, pipes associated with said openings, a light sourcepositioned within one of said pipes, and a light'sensitive elementpositioned within the other of said pipes, a tube slidably mountedwithin one of said pipes and extendable therefrom at right angles intosaid duct to contact the other of said pipes for selectively excludingentrained solids from the portion of the path within said duct traversedby light passing from said light source to said light sensitive elementwithout substantial interference with the normal passage of saidentrained solids through said duct, handles attached to said tube toextend said tube into said duct, and means for creating'a positive gasflow from said pipes and said tube into said duct to remove entrainedsolids when said tube is extended into said duct.

5. An optical system for determining the concentration of entrainedsolids in a gas which comprises a duct having opposed openings in thewalls thereof, pipes associated with said openings, a light sourcepositioned within one of said pipes, and a light sensitive elementpositioned within the other of said pipes, a tube slidably mountedwithin each of said pipes and extendable therefrom at right angles intosaid duct to contact the other tube for selectively excluding entrainedsolids from the portion of the path within said duct traversed by lightpassing from said light source to said light sensitive element withoutsubstantial interference with the normal passage of said entrainedsolids through said duct, handles attached to each of said tubes toextend same into said duct to contact the other tube, and means forcreating a positive gas flow from said pipes and tubes into said duct toremove entrained solids when said tubes are extended into said duct.

JOHN H. RAMSER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name 4 Date 892,241 Freise June 30, 19081,810,739 Vedder June 16, 1931 1,969,626 Simon et al. Aug. 7, 19341,969,627 Simon et a1. Aug. '7, 1934 2,042,095 Grant May 26, 19362,346,690 Larkins Apr. 18, 1944 2,369,966 Hawkins Feb. 20, 1945 FOREIGNPATENTS Number Country Date 438,629 Great Britain Nov. 20, 1935

